I have no experience with the 300wsm but know from what I have read it should be an excellent choice. I do own 2 Tikka's and they have been very accurate and dependable rifles. The trigger on them is the best I have used on a factory setup and is easily adjusted yourself down to about 2 pounds and breaks super clean with no creep at all.
Do you already have the rifle or is it one you are just considering? I believe the Tikka uses one action length foa all chamberings so you are not really getting a shorter action or saving any weight and another caliber choice could be possible for the same weight. That said mine is a 270wsm that I just had to have and the above made no difference to me at all.
I currently have a model 7(7mm-08) and a Savage (270). I am considering buying something in the 30 cal range for elk. I want something I can use for both elk and mule deer. I origian;;y wanted a 338 but thought that might be a little too much recoil for what I need. I narrowed my choices down to 300winmag, 300wsm, and the 300RUM. From what I have been reading and hearing I am leaning towards the 300wsm. I am sure they will all work just fine. I like the weight and barrel length of the Tikka(T3) I think it would be a great choice for backpack hunting or long days of walking.
I have not shot a 300 so I don't know how bad the recoil is but I would for sure replace the recoill pad with a limbsaver or just one of the slip on ones from walmart. They are made by limbsaver but labeled winchester and cost half as much. Another thing I recommend with the Tikka is replacing the factory rings with something better like the gamereaper one piece for about 50 bucks. They are a lot more solid and seem to be the only complaint with the Tikka rifle.
I purchased a Tikka T3 in .300WSM before my first trip west for mule deer. Although I do not still own that rifle, it was a nice rifle and plenty accurate for any hunting situation. I found I was not a big fan of the synthetic parts though. If I was to buy that same rifle again, I'd opt for the .300 WM, as it is the same size action (as already mentioned) and the longer version has just a tad more juice with the heaviest (180 & 200gr) loads commonly found for a .300 mag and also may be a bit easier to find and less expensive in the ammo department as well.
Nothing wrong with a .300SM (I still own one in a Rem 673), but I believe you loose any possible advantage when it's housed in the same action length as a standard length magnum that's been around for as long as the .300WM has.
If you're lucky enough to be on private land and can leave your stand up during the off season you can tie an old piece of cloth or something of the sort to your stand. I like to use an old camo bandana that I have. That way the deer get used to the movement and eventually don't bother even looking up when there is slight movement. This may just give you the time to draw your bow or raise your gun without being detected.